That is, he proposes that the rule about making interrogatives by placing the auxiliary before the subject is to some extent a rule of written English rather than spoken.

My previous post cited two examples that provide crucial evidence of the right sort, but those were open interrogatives - how-questions, in fact (sentences like How radical are the changes you're having to make?).

‘Are you willing to work’ is a common interrogative thrown at women in St Kilda, no matter what their purpose or destination.